Overrunning roller clutches are used in a wide variety of applications where it is desired to selectively transfer power between a pair of relatively rotatable members. Every such clutch has a complement of rollers, each of which rides on a sloped cam ramp machined into one of the rotatable members, generally known as a cam race. Each roller is retained in an individual pocket, which may be part of a separate cage structure mounted to the cam race. Another type of clutch, sometimes referred to as a leg type clutch, has no separate cage, but instead retains each roller in an individual cam slot machined directly into the cam race. Each cam slot is basically U-shaped, with the bottom surface comprising the sloped cam ramp, and with two side walls that confine the rollers within the cam slot.
Since it is necessary to machine the cam ramp as accurately as possible, the ends of the cam ramp will generally be offset from the side walls of the cam slot in order to leave machining clearance. Therefore, some type of corner transition is needed between the ends of the cam ramp and the respective side walls of the cam slot. The two obvious choices are a sharp corner or a circular arc. The former is undesirable because of the stress concentrations that can occur at a sharp corner. A circular arc smoothes out stress well, and is easy to machine. However, in some applications, especially high load ones, a circular arc serving as a corner transition may entail removing more material from the cam race than is desirable.